XAS examination of glutathione–cobalt complexes in solution

In the present work, we have investigated the coordination modes of cobalt with glutathione (γ-l-glutamyl-l-cysteinyl-glycine, GSH). A systematic study of cobalt–GSH complexes at basic and neutral pH has been undertaken with a multi-spectroscopic approach combined with quantum chemistry calculations...

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Bibliographic Details
Published in:Journal of inorganic biochemistry 2015-01, Vol.142, p.126-131
Main Authors: Bresson, Carole, Spezia, Riccardo, Solari, Pier Lorenzo, Jankowski, Christopher K., Den Auwer, Christophe
Format: Article
Language:English
Subjects:
Chemical Physics
Cobalt
Cobalt - chemistry
Coordination Complexes - chemistry
DFT
Glutathione
Glutathione - chemistry
NMR
Physics
X-Ray Absorption Spectroscopy
XAS
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Summary:In the present work, we have investigated the coordination modes of cobalt with glutathione (γ-l-glutamyl-l-cysteinyl-glycine, GSH). A systematic study of cobalt–GSH complexes at basic and neutral pH has been undertaken with a multi-spectroscopic approach combined with quantum chemistry calculations. XAS (x-ray absorption spectroscopy) has been performed at the cobalt K edge in order to shed light into the cation coordination sphere and formal oxidation states. XANES (x-ray absorption near edge structure) enabled to show that in basic and neutral media, cobalt oxidation state is equal to +III and +II respectively. EXAFS (extended x-ray absorption fine structure) provided indications on the donor atoms involved in the coordination with cobalt as well as the bond lengths. DFT (density functional theory)-based calculations and NMR experiments have been performed to assess the most stable structure of the cobalt–GSH complex in basic conditions. Combined XAS, NMR and DFT investigation of cobalt–glutathione complexes at neutral and basic pH is described. Information on the cation coordination sphere, formal oxidation state and most probable conformation of the Co(III)–GSH complex (shown) has been assessed. [Display omitted] •We investigated cobalt–glutathione system in solution in neutral and basic conditions.•We used mainly XAS to examine the coordination mode and the oxidation state of cobalt.•We performed DFT calculations and NMR experiments to support XAS study in basic pH.
ISSN:0162-0134
1873-3344
DOI:10.1016/j.jinorgbio.2014.10.006